Results 241 - 250 of 270

• Hydraulic Stimulation Increases Degasification Rate of Coalbeds
  1/1/1975 - Reports of Investigations
  Coal degasification boreholes drilled from the surface have been successfully hydraulically stimulated to increase the flow of gas from the coal. This Bureau of Mines report describes the hydraulic stimulation procedure for a coalbed, the equipment requ...
• Noise Abatement of Pneumatic Rock Drill
  12/1/1974 - Reports of Investigations
  The principal emphasis of this Bureau of Mines report is on pneumatic drill noise control. Methods are suggested to reduce the noise level by complementing existing machines.
• Cleat in Bituminous Coalbeds
  1/1/1974 - Reports of Investigations
  The natural vertical fracture system in bituminous coalbeds is called cleat. Cleat orientation commonly controls the direction of mining with major development paralleling the face cleat. Previous researchers have categorized the origin of cleat as endo...
• Peak Methane Concentrations During Coal Mining: An Analysis
  1/1/1974 - Reports of Investigations
  Methane concentration peaks were measured at coal mine working faces during entry development. The statistical distribution of peaks was found to be normal or log normal depending on how well the methane was being mixed into the ventilation airstream.
• Tracer Gas as an Aid in Mine Ventilation Analysis
  1/1/1974 - Reports of Investigations
  The Bureau of Mines has successfully used sulfur hexafluoride (SF6) as a tracer gas to measure mine air flows under conditions where conventional methods have failed. SF6 was employed experimentally to measure accurately recirculation of return into int...
• Low-Temperature Evolution of Hydrocarbon Gases From Coal
  1/1/1974 - Reports of Investigations
  Although it is generally believed that coal formation occurred at temperatures below 200 deg c, most experimental work on gas formation from coal has been performed at temperatures between 200 deg and 1,000 deg C. The objective of this Bureau of Mines e...
• Methane and Dust Controls for Longwalls: Pocahontas No. 3 Coalbed, Grundy, Va.
  1/1/1974 - Reports of Investigations
  The periphery of longwall panels in the Pocahontas No. 3 Coalbed is characterized by a zone of reduced permeability that inhibits the natural drainage of methane. However, natural drainage holes drilled during development have been found to reduce the g...
• Degasification of the Mary Lee Coalbed Near Oak Grove, Jefferson County, Alabama, by Vertical Borehole in Advance of Mining
  1/1/1974 - Reports of Investigations
  A 5-hole pattern was drilled from the surface at a site near Oak Grove, Jefferson County, Alabama, to degasify the gassy Mary Lee coalbed in advance of mining. Gas and water production was monitored for 1 year, 4 months to allow gas flow to stabilize fu...
• Using Sulfur Hexafluoride as a Gaseous Tracer to Study Ventilation Systems in Mines
  1/1/1974 - Reports of Investigations
  The Bureau of Mines found sulfur hexafluoride (SF6), released from a lecture bottle, to be an ideal gaseous tracer for studying mine ventilation systems. In a Pennsylvania limestone mine, this technique was useful in evaluating the effectiveness of auxi...
• Methane Control by Isolation of a Major Coal Panel - Pittsburgh Coalbed
  1/1/1973 - Reports of Investigations
  As one of its projects for degasification of major panels of coal prior to mining within them, the Bureau of Mines conducted methane emission studies during development of a set of three headings 1,800 feet in a major coal panel (2,700 by 3,500 feet) wh...